Images: What Are the Possible Side Effects?

BLOOMS AND DEAD ZONES?One concern about iron-fertilized phytoplankton blooms is that they eventually could lead to waters devoid of life?a process that can also occur naturally. In coastal waters off southwest Africa, easterly winds push surface water away from the shore, allowing cold, deep, iron- and nutrient-rich waters to rise to the surface and stimulate blooms, such as this one (the blue-green patch captured by a NASA satellite image) that stretched for hundreds of kilometers off Namibia in November 2007. But when large amounts of marine plants die, bacteria decompose them, using up some of the oxygen available in the water and sometimes creating anoxic ?dead zones? where fish can?t survive. (The MODIS Rapid Response Team at NASA Goddard Space Flight Center)

PLANKTONIC COLLAGE?Biological oceanographer Mary Wilcox Silver assembled this photographic quilt of various microscopic plants, animals, fecal pellets, and other marine detritus resulting from a phytoplankton bloom in the North Pacific Ocean. Fertilizing waters artificially with iron might favor certain species over others and result in unpredictable pathways and consequences in ocean food chains. (Collage by Mary Wilcox Silver, University of California, Santa Cruz)

FROM TOXINS TO CLOUDS?The addition of iron to the oceans could stimulate algal blooms that might be harmful or beneficial. Some scientists caution that iron fertilization could favor certain species of the marine diatom, Pseudo-nitzchia (left), which can sometimes produce domoic acid, a toxin harmful to animals and humans. On the other hand, algae called coccolithophorids (right) release dimethyl sulfide, which eventually encourages cloud formation in the atmopshere that can block solar radiation and help cool the planet. (Photo on left by Mary Wilcox Silver, University of California, Santa Cruz)

WILL SIDE EFFECTS BE GOOD, BAD, OR UGLY??There is a possibility that ocean iron fertilization could increase food supplies that could help dwindling fish stocks. On the other hand, it could also lead to conditions that make jellies more abundant, or cause other ecosystem disruptions. (Fish photo by Tammy Peluso, Jelly photo by Roberto Caucino)